I really don't think the story actually ever gets interesting. Gameplay wise you get to start actually having the real battle system in place by the time you are at about Chapter 3, at which point it become more of pressing X all the time while you switch you Optimas (Paradigms). It really actually a really good system despite a lot of it being "X BUTTON" since buffs/de-buffs and the actual roles will play a major part on whether or not you actually do well in the game. As far as the linear nature of the game goes, you have to get to Chapter 11 before you're given any sort of freedom. That takes anywhere from 15 to 25 hours depending on whether or not you're rushing the game. If you hate the battle system by the chapter you are probably a good 10 hours in chances are you'll hate the game because the side-quests are more or less things like hunts/marks and really that's just more battling.
